Electrical resistor and method for its manufacture

Abstract

SMD current-sense resistors are manufactured by dividing a drawn laminated wire structure that consists of a core of a resistive alloy and a jacket made of copper, e.g. After removing part of the copper jacket, jacket sections used as connector contact layers remain only at the ends of the resistor.

What is claimed is:  
     
         1 . Electrical resistor, in particular, for measuring current, with a resistive element ( 1 ) that consists of a metal resistive alloy, and with two connector contact elements that are arranged at a distance from one another on opposite ends ( 3 ) of the resistive element and consisting of a metal with a higher electrical conductivity than the resistive alloy, characterized by the fact that jacket sections ( 4 ) which surround the circumference of the resistive element ( 1 ) in tubular fashion and are formed of welded band or tube material are provided as the connector contact elements.  
     
     
         2 . Resistor according to  claim 1 , characterized by the fact that the resistor consists of a drawn laminated wire structure, the jacket of which is removed between the connector contact layers ( 4 ).  
     
     
         3 . Resistor according to  claim 1  or  2 , characterized by the fact that the resistive element ( 1 ) is surrounded by an insulating body ( 6 ) between the jacket sections ( 4 ), wherein said insulating body has at least one flat outer surface  97 ) for placing the resistor onto a circuit board in the form of a surface-mount device.  
     
     
         4 . Method for manufacturing electrical resistors by utilizing a wire material of a metal resistive alloy, characterized 
 in that a wire core consisting of the resistive alloy is surrounded by a jacket of a metal that has a higher electrical conductivity than the resistive alloy;    in that the jacket is welded such that a closed tube is formed;    in that the laminated wire structure formed of the wire core and its jacket is drawn to a smaller diameter, and    in that the drawn laminated wire structure is separated into parts that form the individual resistors;    wherein an axially central section of the jacket is removed on each individual resistor such that jacket sections ( 4 ) that are separated from one another and serve as connector contact elements remain only at the ends ( 3 ) of the resistor.    
     
     
         5 . Method according to  claim 4 , characterized by the fact that the central jacket section is removed by means of turning.  
     
     
         6 . Method according to  claim 4  or  5 , characterized by the fact that, during the removal of the central jacket section, part of the underlying resistive material is also removed until the desired diameter is obtained.  
     
     
         7 . Method according to one of claims  4 - 6 , characterized by the fact that a body ( 6 ) of insulating material which has at least one flat outer surface  97 ) is applied onto the section ( 2 ) of the resistive element  91 ) which is located between the jacket sections  94 ).  
     
     
         8 . Method for manufacturing electrical resistors by utilizing a wire material of a metallic resistive alloy, characterized 
 in that a wire core consisting of the resistive alloy is surrounded by a jacket of a metal that has higher electrical conductivity than the resistive alloy  6 ;    in that the jacket is welded such that a closed tube is formed;    in that the laminated wire structure formed of the wire cord and its jacket is drawn to a smaller diameter; and    in that the drawn laminated wire structure is divided into disks that form the individual resistors;    wherein sections ( 14 ′) of the jacket that are located opposite one another on the disk circumference are removed from each individual resistor together with the respectively adjacent section ( 10 ″) of the resistive alloy such that jacket sections  914 ) that serve as connector contact elements remain only at the two ends of the remaining resistive element ( 10 ).    
     
     
         9 . Method according to one of claims  4 - 8 , characterized by the fact that the drawn laminated wire structure is annealed in order to realize a diffusion layer between the metal of the connector contact elements and the alloyed metal.  
     
     
         10 . Utilization of the resistor according to one of the preceding claims for measuring currents.  
     
     
         11 . Utilization of a resistor according to one of the preceding claims as an SMD component.